Air compressor of the multicylinder reciprocating type



se t; 20; 1932.

H. R. RICARDO AIR COMPRESSOR OF THE MULTICYLINDER RECiI-ROCATING TYPE 2Sheets-Sheet 1 Filed April 13, 1932.

Sept. 20, 1932. H. R. RICARDO 1,878,325

I AIR COMPRESSOR OF THE MULTICYLIND ER RECIPROCATING TYPE Filed April13, 1932 2 Sheets-Sheet 2 Patented Se t '20, 1932 UNITED STA TESI-PATENHARRY Rnnrrr RICARDO, on tonn'on, ENGLAND AIR oonrrnnsson on THEmonrrovnrnnnn nnclrnoonrme TYPE Application filed April 13, 1932, SerialNo. 605,099, and in GreatiBritain Ap rll 28, 1931.

This invention relates .to of the multi-cylinder reciprocating type inwhich inlet and delivery ports in each cylin-,

- der are controlled .by one or more sleeve valves, and has for itsobject to provide improved means for unloading such compres- To this endin an air compressor of the above type according to the presentinvention, there is combined with a cylinder group comprising two ormore cylinders the movements of the istons in which have suchphase-relations ip that the sum of the volumes of'the compression spacesof such cylinders remains constant or only varies slightlye throughoutthe cycle of operations, unloadin mechanism comprising one or more vaves (hereinafter termed unloadingvalves) whereby the workin spaces ofthe cylinders in such group can e brought into direct communication withone another, and a nonreturn valve in the delivery passage leading fromeach cylinder or in a common delivery passage leadmgfrom two or morecyllnders' constituting the group or part of the group.

' It will thus be seen that when the unloading and forwards betweenthese cylinders but valve or valves are opened to bring-the compressionspaces of the cylinders of a group into communication, air will becaused by the pistons in such cylinders to flow backwards no air will bedelivered,-whi1e the non-return valve or valves will close the deliverypassage flow,the non-'return valve or valves will close or assages fromthe cylinders toprevent bac ow of air'into the cylinders ,from thedelivery passage. 1 a

' Preferably the action -ofthe non-return valve-or valves is such thatwhereas such,

.valve or valves will be maintained continu ously 'open'during normaloperatron of the compressor n spite of .cyclic variations inautomatically when delivery of air by the compressor c e'ases,'forexample when the unloadlng valves are opened. "Thus repeated openingandclosing of the non-return valve or valves during normal operation of thecompressor is'prevented. 4 e unloading valves may be of various formsbutconveniently the unloading mech air compressors livery passages fromthe cylinders which lie on the side of the non-return valve or valvesadjacent to the cylinders.

The means for opening the unloading valves may vary but in onearrangement these valves are adapted to be opened by one or more pistonseach disposed within a cylinder and adapted to be acted upon by fluidpressure derived from thereceiver or the like to which the compressordelivers air or gas. A single piston may control all the unloadingvalves for the cylinders constituting each group, or a separate pistonmay act on each valve, for example in the case of oppet valves by adirect connection between t evalve stem and piston. In anycase a relayvalve may so be provided which normally admits atmospermit flow of airunder pressure thereto from the receiver so as to open the unloadingvalves when the pressure in the receiver reaches or exceeds apredetermined value whereby the unloading valves are automaticallyopened whenever the ressure inthe receiver exceeds a redeter'mmed valueand flare automaticallyc osed when this pressure drops belowsllchpredetermined value. Alternatively the arrangementmay be such that theunloading valves are automatically opened when thepressu're in thereceiver exceeds one predetermined value but vare not 1.

sleeve valve E and these parts.

automatically closed again until the pressure has dropped below'someother and lower predetermined value, thus tending toprevent Figure 1 isa sectional side elevation of a two-cylinder compressor accordingto thisinvention, j r

Figure 2 is aplan partly in section of the engine shown in Figure 1, and

FigureB is a section on the line 33 of Figure 2.

In the construction illustrated the compressor comprises a crank case Aon which is mounted a cylinder block B containing two cylinders havingcylinder liners B and surrounded by a water jacket B having an inletpassage B and an outletpassage B.

Formed in the wall of each cylinder liner B is a series of slot-likeinlet ports C communicating with an induction belt C the part C otwhichlying between the cylinders iscomlnon to both cylinders. Extending intothe upper end ofeach cylinder is a plug-like cylinder head D and anannular space D is 16a between .the lower end of each plug-like cylinderhead and the. upper end of its associated liner 13 such spaceconstituting the.

delivery port from the cylinder.

Disposed within each cylinder liner is a sleeve valveE the upper end ofwhich hes around and is closed by the plug-like cylinder head 1),packing; rings. E being provided respectively in grooves in the cylinderhead D and in the upper end of the cylinder liner B to prevent escape offluid between the Each sleeve valve is provided on the one hand with aseries of slot-like inlet ports E adapted to cooperate with theslot-like inlet ports C in the cylinder liner surrounding it and on theother hand with a ring of delivery ports E adapted to cooperate with thedelivery port D A piston F coupled by a connecting rod F to a crankshaft F mounted in bearings in the crank case A reciprocates directlywithin each sleeve, the cranks to which the two pistons F are coupledbeing angularly displaced by 180. A combined oscillating andreciprocating movement is imparted .to each sleeve by mechanism, knownin itself,-com

E is such that the ports E come into communication with the ports C andthe ports E come into communication with the delivery port D twiceduring each cycle of each sleeve valve E. Thus, assuming a valve E to bein the position shown for the valve in the lefthand cylinder of Figure1, thatis to say the position in which the valve has just completed oneof the two portions of its movement which are mainly'oscillatory and isabout to begin that portion of its movement which is mainlyreciprocating in an upward direction, this upward movement will firstcarry the ports E into comunication with the port D so that delivery cantake place through the ports E and D during the last part of the travelof the piston in the upward direction. At the end of the upward movementof the piston,

the continued upward movement of the sleeve will carry the ports E abovethe port D The movement of the sleeve now begins to be mainlyoscillatory and this movement will cause the ports E to be moved acrossthe upper ends of the ports G as the piston descends so that air can bedrawn in through the ports E C. At or towards the end of the downwardmovement of the piston the ports E will have been carried completelyacross and out of register with the ports C and the movement of thesleeve will begin to be mainly reciprocating in a downward direction sothat as the piston again ascends the ports E will move downwards intoregisterwith the port D during the end portion of the upward stroke ofthe piston and will again be carried out of register with these portswhen the piston reaches its upper dead centre. The. movement of thesleeve will now be mainly oscillatory again and will cause the portsE to-move across the lower ends of the ports C duringthe subsequent suctionstroke of the through the ports E and C. It will therefore be seen thatalthough the valve E is only operative at half crankshaft speed yet thedelivery ports and suction ports are each opened twice during each valvecycle so as to connect the working chamber of each cylinder to theinduction belt during each suction and to the delivery .chamber duringeach delivery stroke.

The delivery ports D communicate with annular delivery chambers H andthese two chambers H communicate with one another and with a commondelivery passage H as shown in Figure 2. Formed in each plug-likecylinder head D is a port D whichis normally piston so that'air canagain be drawn in.

with a delivery pipe H through a non-return valve H- of the poppet typewhich is acted upon by a light spring H tending to maintain it alwaysclosed and is controlled by a dashpot,device-comprisi ng a piston'H atone end of the valve stem having a small leaka e passage indicated at Hand disposed'within a cylinder H filled with oil. The arrange ment issuch'that the valve H will be opened automatically by the pressure ofair-delivered .by the compressor and the dash-pot device H, H willprevent this valve closing under;

H the action of its spring during cyclic varia- "each valveD is a collarJ from which extend trunnions J which are connected by llnks J to apivot pin J which passes through an intermediate point inalever K .oneend of which is pivoted to a bracket K on the cylinder head, while itsother end bears on the upper end of a piston L which is common to bothlevers K.

The piston L is arranged within a cylinder L having an opening, 2 at itslower end, a

' light helical spring L acting on the lower end of the piston andserving always to maintain its upper end in contact with the. ends ofthe leversK. The cylinder L is located within a chamber'M partiallyfilled with oil so that I reduced diameter so as to the opening L isalways below oil level and this. chamber communicates through a passageM with a valve whereby the chamber. M can be brought into communicationeither with the atmosphere or with the pressure in the delivery pipe Hfrom the compressor.

This valve comprises a cylinder N the'lower end of which is connected bya pipe N to the delivery pipe H Arranged within the cylv lnder'N is apiston-N hav1ng afportion N of provide an annular chamber N whichcommunicates through a assage N in the piston with the atmosp ere and,when the valve is in the position shown in Figure 3 also communicateswith the passage M sothat the chamber M and hence the underside of thepiston L is subject only to atmospheric pressure. The piston N carries aweight N at its upper end which normally tends to maintain it in theposition indicated in Figure 3, but when the pressure in the deliverypipe H exceeds a predetermined value, this pressure will raise thepiston N so that 1ts lower end uncovers the passage M whereupon airunder pressure from the delivery pipe N will be delivered to the chamberM' so that this pressure will act on the underside of the piston L andthus raise this piston and thereby act through the levers K to lift boththe valves D The operation of the compressor is asfollows. During normaloperation air will be drawn during each suction stroke of each piS- tonthrough the inlet orts E and C lIl' its. associated cylinder, an will bedelivered during each delivery stroke through the ports E and D intothe-chambers H and thence through the common delivery passage H and thevalve H into-the delivery pipe H If, now, the pressure in the pipe Hexceeds a predetermined value, this pressure will act through the pipe Non the piston valve N 2 so as to raise this piston valve and therebyadmit air under pressure through the passage M to the chamber M. Thisair will act through the opening L .on the piston L so as I 4 to raisethis piston and thereby act through the levers K to open both theunloading valves 1) against the action of their sprlngs 13*. Thus thecompression spaces of the two cylinders will be brought, through thepassa es H and the common delivery passage into communication with oneanother and since the cranks associated with the two p1stons F areangularly displaced by 180, it will be seen that with the two valves Dopen, air will simply be caused to travel backwards andforwards betweenthe compression spaces of the cylinders and no air will be dellveredthrough the valve H andpipe H The valve H will therefore close under theaction of its spring so as to prevent back flow of air from the deliveryp1pe H into the common delivery passage H If the air pressure in thedelivery pipe H drops, owing for example to the consumptlon of air, thepiston valve N :will again move into the position indicated. in Figure 3so as to bring the chamber M- again into communication with theatmosphere. The piston ,L will now descend under the action of thelevers K due to the force of the valve springs 'D whereupon delivery ofair by the compressorwill again begin, the valve H will be opened andthe compressor will continue 7 in operation until the pressure in thepipe H again exceeds the predetermined valuewhen v the compressor willagain automatically be unloaded as described above.

It is to beunderstood that although. in 1 the construction illustratedmeans are provided for unloading, the compressor automatically when thecompression pressurein the delivery pipe exceeds a predetermined value,the invention 'isnot limited to such an,

arrangement but that unloading mechanism accor ing-to this invention maybegoperated either automatically or at will. Further, the

invention may be applied to multi-cylinder reciprocating air.compressors having more than two cyllnders and 1n such cases the un.

loading may beetfected-bybrin ing the com- .125

pression spaces of all the cylin ersofflthe air compressorintocommunlcatlon or by brlnging thecompression' spaces-of two ormor'egroups of cylinders into communication, the

groups being selected so that the sum of the volumes of the compressionspaces of the cyl:

inders in each group remains substantially constant throughout theoperation of the com pressor.

' What I claim as my invention and desire to secure by Letters Patentisout the cycle of operations, one or more valves whereby the workingspaces of the cylinders in each group can be brought into continuousdirect communication with one another, and a non-return valve inthedelivery passing leading from each cylinder.

2. A compressor for gas of the multi-cylinder reciprocating typeincluding in combination at least two cylinders having inlet and outletports therein, sleeve valves controlling these ports, pistons in thecylinders the movements of which have such phase-relationship that thesum of the-volumes of the compression spaces of the cylinders remainswithin small limits the same throughout the cycle of operations, one ormore valves whereby the working spaces of the cylinders can be broughtinto continuous direct communication with one another, and a non-returnvalve in the delivery passage leading from each cylinder.

3. A compressor for gas of the multi-cylinder reciprocating typeincluding in combination at least one group of cylinders having inletand outlet ports therein, each group including at least two cylinders,sleeve valves controlling the inlet and outlet ports, pistons in thecylinders, the movements of the pistons in each group havingsuchphase-relationship that the sum of the volumes of the compression spacesof the cylinders in each group re.-

out the cycle of operations, one or more valves whereby the workingspaces of the cylinders in each group can be brought into continuousdirectcommunication, with one another, and

open during normal operation of the com-- der reciprocating typeincluding in combination at least two cylinders havlng inlet and a anon-return valve in the delivery passage leading from each cylinder, thenon-return valve being so constructed and arranged that whereas it willbe maintained continuously pressor in spite of cyclic flow variations ita will close automatically when delivery of fluid ceases.

4. A compressor for gas of the multi-cylinoutlet ports therein, sleevevalves controlling these ports, pistons in the cylinders the movementsof which have such phase-relationship that the sum of the volumes of thecompression spaces of the cylinders remains within small limits the samethroughout the cycle of operations, one or more valves whereby theworking spaces of the cylinders can be brought into continuous directcommunication with one another, and a non-return valve 'in the deliverypassage leading from each cylinder, the non-return valve being soconstructed and arranged that whereas it will be maintained continuouslyopen during normal operation of the compressor in spite of cyclic flowvariations it will close automatically when delivery of fluid ceases.

5. A compressor for gas of the multi-cylinder reciprocating typeincluding in combination at least one group of cylinders having inletand outlet ports therein, each group including at least two cylinders,sleeve valves controlling the inlet and outlet ports, pistons in thecylinders, the movements of the pistons in each group having suchphase-relationship that the sum of the volumes of the compression spacesof the cylinders in each group remains within small limits the samethroughout the cycle of operations, one or more valves whereby theworking spaces of the cylinders in each group can be brought intocontinuous direct communication with one another, a non-return valve inthe delivery passage leading from'each cylinder, and a dashpot socontrolling the non-return valve that .whereas it will be maintainedcontinuously open during normal operation of the compressor in out thecycle of operations, one or more valves mains within small limits thesame through-c whereby the working spaces of the cylinders can bebrought into continuous direct communication with. one another,anon-return valve in the delivery passage leading from each cylinder,and a dashpot so controlling the non-return valve that whereas it willbe bination at least one group of cylinders having inlet and outletports therein, each group including at least two cylinders, sleevevalves controlling the inlet and outlet ports, pistons in the cylinders,the movements of the pistons in eachv group having such phase-relagroupremains within small limits the same throughout the cycle of operations,a springcontrolled poppet valve in each cylinder headadapted to movewhen opening in a direction away from the cylinder, the poppet valves inthe heads of the cylinders consti tuting each group communicating with acommon passage through which, when these poppet valves are opened, theworking chambers of all the cylinders in each group are brought intodirect communication, a delivery passage leading from the common passageand a non-' chamber, and a non-return valve 1n each of return valve inthis delivery passage.

8. A compressor for gas of the multi-cylinder reciprocating typeincluding in combination at least two cylinders having inlet and outletports therein',.sleeve valves controlling these ports, pistons inthecylinders the movements of which havev such phase-relationship that thesum of the volumes of the compression spaces of the cylinders remainswithin small limits the same throughout the cycle of operations, aspring-controlled poppetvalve in each cylinder head adapted to move whenopening in a direction away from the cylinder, poppet valves in theheads of the two cylinders com municating with a common passage throughwhich, when the poppet valves are open, the working chambers of the twocylinders are brought into direct communication, a delivery passageleading from the common passageand a non-return valve in the deliverypassage.

' 9. A compressor for gas of the multi-cylinder reciprocating typeincluding in combination at least two cylinders having inlet and outletports therein, Sleeve valves controlling these ports, pistons in thecylinders the movements of whichha've such phase-relationship that thesum of the volumes of the compression spaces of the cylinders remainswithin small limits the same throughout the cycle of operations, aspring-controlled poppetvalve in each cylinder head adapted to move whenopening in a direction away from the c linder, the poppet valves in theheads o the cylinders communicating with a common passage through which,when the poppet valves are open, the working chambers of the twocylinders are brought into direct communication, a delivery passageleading from the common passage and a non-return valve in the deliverypassage, and-*a dashpot control-. 1n

the non-return valve so that whereas it 'wil be maintained continuouslyopen durmg normal operation of the compressor in spite of cyclic flowvariations it will close automatically when delivery of fluid ceases.

10. A compressor for gas of the multi-cylinderreciprocating typeincluding in combinationat least one group of cylinders having portscommunicating with one another through a common delivery chamber, each vcylinder group including at least twocylinders, sleeve valves controllinthe inlet and outlet ports, pistons in the cy inders in each;

group the movements of which have such phase-relationship that the sumof the volumes of the compression'spaces of the cylinders in each groupremains within small limcation with the common delivery chamber, at 5least one delivery passage'leadingfrom this the said delivery passages.

11. A compressor for gas of'the multicylinder reciprocating typeincluding in combination two cylinders having inlet ports and. outletPorts which communicate with a common de 1 very chamber, sleeve valves.con-

trolling the inlet and outlet ports, pistons in the cyllnders the movemntsjof which have such phase-relationship t at-the sum of the volumes ofthe compression spaces of the cylinders remains within small limits thesame throughout the cycle of operations, one or more valves whereby theworking spaces of the cylinders can be brought into continuous directcommunication with the common de livery chamber, a delivery passageleading from such chamber, and a non-return valve in the deliverypassage.

12. A compressor for gas of the 'multi-w cylinder reciprocating typeincluding in combination two cylinders having inlet 'ports and outletports which communicate with" a common delivery. chamber, sleeve valvescontrolling the inlet and outlet ports, pistons in the cylinders themovements of which have such phase-relationship that the sum of thecylinders remains within small limits the same throughout the c cle ofoperations, one or more valves where y the working spaces of thecylinders can be brought into continuous direct communication with thecommon delivery chamber, a delivery passage leading from such chamber, anon-return valve in the delivery passage, and a dashpot that whereasthis valve will be maintained continuously open during normal operationof the compressor in spite of cyclic flOW'VfiIlations it will closeautomatically when delivery of fluid ceases.

volumes of the compression spaces'of the 1 device controlling thenon-return valve so 13. A compressor-for the m'ulti-cylinderreciprocating type including in combination at least one group ofcylinders having inlet and outlet ports therein, the group including atleast two cylinders, sleeve valves controlling the inlet, and outletports, pistons in the cylinders in each groupthe moveinlet ports andoutlet ports therein, the outlet p5 ments of which have suchphase-relationship sion spaces of the cylinders in each groupremains'within small limits the same throughout the cycle of operations,one or more valves whereby the working spaces of the cylinders in eachgroup can be brought into continuous direct communication with oneanother, a non-return valve in the delivery passage leading from eachcylinder, and

' means for automatically opening the unloading valves for bringing thespaces of the cylinders in each group 'into continuous directcommunication comprising at least one control cylinder, a piston in eachcontrol cyl-' inder, an operative connection between this piston and anunloading valve and means for delivering to each cylinder fluid underpressure from the receiver to, which the compressor delivers gas.

14. A compressor for gas of the multicylinder reciprocating typeincluding in combination at least one group of cylinders having inletand outlet ports thereln, each group including at least two cylinders,sleeve valves controlling the inlet and outlet ports, pistons .in thecylinders in each group the movements of which have suchphase-relationship' that the sum of the volumes of the compressionspaces of the cylinders in each group remains within small limits thesame throughout the cycle ofoperations, a springcontrolled poppet valvein each cylinder head adapted to move when opening in a direction awayfrom the cylinder, the poppet valves in the heads of the cylindersconstituting each group communicating with a common passage throughwhich, when these poppet valves are opened, the working chambers of allthe cylinders in each group are brought into direct communication, adelivery passage leading from each common passage, a non-return valve inthe delivery passage and means for opening the poppet valves com--rising at least one control cylinder, a piston I in each controlcylinder an operative convalve, and means for delivering fluid 'underpressure to each control cylinder from the nection between this pistonand a poppet receiver to which the compressor delivers gas.

15. A compressor for gas of the multicylinder reciprocating typeincluding in combination at least two c linders having inlet and outletportstherein, sleeve valves controlling these ports, pistons in thecylinders the movements ofwhich have such phaserelationship that the sumof the volumes of the compression spaces of the cylinders remains within1 small limits the same throughout the cycle of operations,aspringcontrolled poppet valve in each cylinder head adapted to movewhen opening in a direction away from the cylinder, the ports controlledby the poppet valves in the heads of the two cylinders communicatingwith a common passage through which, when the bers of the two cylindersare brought into direct communication, a delivery passage leading fromthe common passage a nonreturn valve in the delivery passage, and meansfor openingthe poppet valves comprising at least one control cylinder, apiston in each control-cylinder, an operative connection between thispiston and a poppet valve and means for delivering fluid under pressureto each control cylinder from the receiver to which the compressordelivers gas.

16. A compressor'for gas of the multicylinder reciprocating typeincluding in combination at least one group of cylinders having inletand outlet ports therein, the group including at least two cylinders,sleeve valves controlling the inlet and outlet ports, pistons in thecylinders in each group the movements of which have suchphase-relationship that the sum of the volumes of the compression spacesof the cylinders .in each group remains within small limits the samethroughout the cycle of operations, one or more valves whereby theworking spaces of the cylinders in each group can be brought intocontinuous direct communication with one another, a non-return valve inthe delivery passage leading from each cylinder, means for automaticallyopening the unloading valves for'b-ringing the compression spaces of thecylinders in each group into continuous direct communication comprisingat least one control cylinder, apiston ineach control .cylinder, and anoperative connection between this piston and an. unloading valve, andmeans for delivering to each control cylinder fluid under pressure fromthe receiver to which the compressor delivers gas comprising a valvewhich normally admits atmospheric pressure only to the said controlcylinder but when the receiver reaches a predetermmed value actsautomatically to cut oflt' the control cylinder from atmosphericpressure and permit flow of as thereto from the receiver.

1 A compressor for gas of vthe multi cylinder reciprocating typeincluding in combination at least one group of cylinders having inletand outlet ports therein, each group including at least two cylinders,sleeve valves controlling the inlet and outlet ports, pisressure in thetons in the cylinders in each group the movements ofwhich have suchphase-relationship that the sum of the volumes of the compression spacesof the cylinders in each group v remains within small limits the samethroughout the cycle of operations, a spring-controlled poppet valve neach cylinder head adapted to move when opening in a direction away fromthe cylinder, the poppet valves in theheads of the cylindersconstituting eachgroup communicating with a common passage throughwhich, when. these poppet valves are opened, the Working chambers of allthe cylinders in each group are brought into direct communication, adelivery pas. sage leading from such common passage '3.

non-return valvein the delivery passage,

means for opening the poppet valves comprising at least one controlcylinder, a piston in each control cylinder, an operative connectionbetween this piston and a poppet valve and means for delivering fluidunder pressure to each control cylinder from the receiver to which thecompressor delivers gas, and means for controlling the flow of fluidunder pressure from the receiver in each control cylinder, comprising avalve which normally admits atmospheric pressure only to the saidcontrol cylinder but when the pressure in the receiver reaches a prede-*termined value acts automatically to cut off the control cylinder fromatmospheric p-ressure and permit flow of gas thereto from the recelver.i Y

' 18. A compressor for gas of the multi-cylinder reciprocating typeincluding in com bina-tion at least two cylinders having inlet andoutlet ports therein, sleeve valves controlling these ports, pistons inthe cylinders the movements of which have such phaserelationship thatthe sum of the volumes of the compression spaces of the cylindersremains within small limits the same throughout the cycle of operations,a spring-controlled poppet valve in each cylinder head adapted to movewhen opening in a direction away from the cylmder, the poppet valves inthe heads of the two cylinders communicating with a common passagethrough which, when the poppet valves are opened, the working chambersofthe two cylinders 40 are brought into direct communication, a deliverypassage leading from the common passage a non-return valve inthedelivery passage, means for opening the poppet valves comprising atleast one control cylinder, a piston in each control cylinder andoperative connection between this piston and a po pet valve and meansfor delivering flllld' under pressure to each control cylinder from thereceiver to which the compressor deliv- 6 ers gas, and means forcontrolling the flow of fluid under pressure from the receiver in eachcontrol cylinder, comprising a valve which normally admits atmosphericpressure only to the said control cylinder but when the pressure in thereceiver reaches a predetermined value acts automatically to cut ofi thecontrol cylinder from atmospheric pressure and permit flow of gasthereto from the receiver.

I m In testimony whereof I have signed my name to this specification.HARRY RALPH RICARDO.

